Glare, dazzle or flash-blindness is a consequence of a light differential that is too high for the adaptation capability of the human eye. While operating an aircraft or ground-based vehicle, glare can significantly reduce an operator's visual comfort, cause temporary blindness and inability to properly operate an aircraft or vehicle, and even prolonged decline in visual performance.
Glare varies considerably depending on whether the source of light differential is situated at the center or at the edge of an operator's field of vision. The zone most sensitive to glare effects is the center of the field of vision, which corresponds to the central part of the retina in the human eye.
When an intense light differential is situated at the center of an operator's field of vision, the inconvenience experienced may be intense and prolonged over time, even after the glare has ceased. This may be detrimental to the operator's concentration, particularly while trying to operate an aircraft or vehicle.
Therefore, devices for protecting against glare effects are particularly necessary so as to ensure comfort and optimal safety while operating an aircraft or vehicle.
While operating a land-based vehicle, such as for example an automobile, glare may be due to light from the sun during the day, including direct sunlight, sunlight that reflects off other automobile surfaces, or sunlight reflecting off reflective road surfaces. At night, glare experienced by a vehicle operator may be due to headlights from other vehicles, including for example overly intense lighting caused by poorly adjusted automobile headlights, or other exterior sources of light, such as for example street lights.
While operating an aircraft, glare may be caused by light from the sun, especially during the aircraft approach and takeoff phases when the elevation of the sun is low with respect to the horizon.
The devices for protecting against glare caused by sunlight that are traditionally used in either aircraft or other vehicles are generally mechanical devices, such as sunshades or other moveable panels.
At night, no effective system exists which makes it possible to reduce glare. In such a case, an operator can simply avoid staring directly at the glaring object in order to protect the accommodation of his or her eyes to the light differential. It is understood, however, that this solution is not suitable for safe operation of aircraft or vehicles as it reduces operator concentration and awareness.
In passenger transport aircraft for example, the flight decks comprise light-blanking panels which are mounted on the ceiling of the flight deck and which can be moved so as to be positioned facing at least one of the windows of the flight cabin, in order to reduce the light transmission area. The panels can be of fixed size and generally intended to blank out an entire window. However, they are not practical to manipulate due to the restricted size of the flight cabin, or with the loss of visual use of an entire window for operational purposes. This manipulation may also become inconvenient during the takeoff or approach maneuvers, when the pilot has to concentrate on his or her piloting task and is adversely affected by glare. Finally, the integration of these mechanical items into the flight cabin requires particular fitting out of the instruments and control panels.
In aeronautics, certain concepts have been proposed in order to alleviate these problems. Mention has been be made especially of electronic devices of sunshade type. One of the proposed solutions uses electrochromic glazings which become darker or lighter under the effect of an electrical voltage whose amplitude is in turn dependent on a voltage provided by a brightness sensor. Such sunshade devices have been tested on trial craft, where certain windows of whose flight deck were provided with electrochromic glazings disposed inside the flight deck. More precisely, layers of electrochromic glazings were disposed on the windows of the flight deck.
However, these sunshade devices decreased the luminous transmission too considerably and over the entire surface area of a window when they were activated and have not therefore been adopted for their use in a flight deck.
Consequently, one of the objectives of present subject matter is to provide systems, methods and computer readable media for protecting against glare caused by light from the sun or luminous objects and which allows progressive and localized attenuation of the light.